An electric energy meter clock self-calibration device and method

Abstract

The application discloses an electric energy meter clock self-calibration device and method, wherein the electric energy meter clock self-calibration device comprises a common time-keeping crystal oscillator and a temperature-compensated crystal oscillator, wherein a standard frequency signal output by the temperature-compensated crystal oscillator is used for compensating a to-be-calibrated frequency signal output by the common time-keeping crystal oscillator, and a time-keeping signal is output. The internal clock reference self-calibration method of the electric energy meter is realized, and the system calibration workload is saved without relying on external, remote and high-precision clock source calibration.

Description

Technical Field

[0001] This application relates to the field of smart energy meter technology, and in particular to an energy meter clock self-calibration device and method. Background Technology

[0002] With the increasing scarcity of energy resources and the growing severity of environmental problems, energy conservation and emission reduction have become important issues of global concern. As a basic device for measuring energy consumption, the accuracy of electricity meters directly affects the fairness and accuracy of energy billing. Traditional electricity meter clock circuits suffer from problems such as clock frequency drift and poor long-term stability, affecting the accuracy of electricity measurement. Summary of the Invention

[0003] To address the technical problems existing in the prior art, this disclosure provides a clock self-calibration device and method for electricity meters.

[0004] According to one aspect of this application, a self-calibrating device for an electricity meter clock is provided, comprising: a standard timekeeping crystal oscillator and a temperature-compensated crystal oscillator, wherein...

[0005] The standard frequency signal output by the temperature-compensated crystal oscillator is used to compensate the frequency signal to be calibrated output by the ordinary timekeeping crystal oscillator, and a timekeeping signal is output.

[0006] Optionally, the energy meter clock self-calibration device further includes: a first frequency divider, a frequency multiplier, a phase detector, a second frequency divider, a multiplier, a counter, and a phase-locked calculation module, wherein...

[0007] The temperature-compensated crystal oscillator outputs a standard frequency signal to the first frequency divider, and outputs a first frequency divided signal to the first input port of the phase detector according to the first frequency division factor.

[0008] A standard time-keeping crystal oscillator outputs the frequency signal to be calibrated to a frequency multiplier. Based on the multiplication factor, it outputs a multiplied signal to a second frequency divider. Based on the second division factor, the multiplied signal is divided, and the second divided signal is output to the second input port of the phase detector.

[0009] The phase detector performs phase detection on the first frequency division signal and the second frequency division signal, and outputs the phase difference signal between the first frequency division signal and the second frequency division signal;

[0010] The multiplier receives the phase difference signal and the standard frequency signal, multiplies them, and outputs the frequency pulse signal within the phase difference signal time period to the counter.

[0011] The counter counts the frequency pulse signal and inputs it into the phase-locked calculation module to obtain the phase difference corresponding to the phase difference signal;

[0012] The phase-locked calculation module adjusts the multiplication factor of the frequency multiplier according to the phase difference until the phase difference between the first and second frequency division signals is the initial phase difference. The frequency signal to be calibrated is amplified according to the adjusted multiplication factor and used as a timekeeping signal and output.

[0013] Optionally, the formula for the change of the frequency signal to be calibrated for a conventional time-keeping crystal oscillator is:

[0014] f(T)=f0*[1-a*(T-T0) 2 ]

[0015] In the formula, f(T) is the frequency signal to be calibrated, f0 is the nominal frequency, i.e., the timed output, T0 is the standard temperature (25℃), a is the parabolic coefficient of the quartz crystal, and T is the ambient temperature.

[0016] Optionally, the formula for calculating the phase difference is:

[0017]

[0018] In the formula, f os The frequency signal to be calibrated is f. os = f(T), k is the harmonic multiplier, m1 is the first divider multiplier, m2 is the second divider multiplier, f ref The standard frequency signal is t0, which is the initial phase time difference between the two input signals, and n is the number of measurement cycles.

[0019] Optionally, the formula for calculating the frequency signal to be calibrated is:

[0020]

[0021] Optionally, in the event of a power failure in the self-calibration device of the electricity meter clock, low-power compensation is performed based on the timekeeping signal and phase difference at the time of power failure, and the compensated timekeeping signal is output.

[0022] According to another aspect of this application, a method for self-calibrating the clock of an electricity meter is provided, implemented using any of the aforementioned electricity meter clock self-calibration devices, comprising:

[0023] A standard frequency signal is output to the first frequency divider through a temperature-compensated crystal oscillator. Based on the first frequency division factor, the first frequency divided signal is output to the first input port of the phase detector.

[0024] The frequency signal to be calibrated is output through a regular time-keeping crystal oscillator to a frequency multiplier. The frequency multiplier signal is output to the second frequency divider according to the frequency multiplication factor. The frequency multiplier signal is divided according to the second frequency division factor, and the second frequency divided signal is output to the second input port of the phase detector.

[0025] The phase detector performs phase detection on the first and second frequency division signals and outputs the phase difference signal between the first and second frequency division signals.

[0026] The multiplier receives the phase difference signal and the standard frequency signal, multiplies them, and outputs the frequency pulse signal within the phase difference signal time period to the counter.

[0027] The frequency pulse signal is counted by a counter and input into the phase-locked calculation module to obtain the phase difference corresponding to the phase difference signal;

[0028] The phase-locked calculation module adjusts the multiplication factor of the frequency multiplier according to the phase difference until the phase difference between the first and second frequency division signals is the initial phase difference. The frequency signal to be calibrated is amplified according to the adjusted multiplication factor and used as a timekeeping signal for output.

[0029] Optionally, the formula for the change of the frequency signal to be calibrated for a conventional time-keeping crystal oscillator is:

[0030] f(T)=f0*[1-a*(T-T0) 2 ]

[0031] In the formula, f(T) is the frequency signal to be calibrated, f0 is the nominal frequency, i.e., the timed output, T0 is the standard temperature (25℃), a is the parabolic coefficient of the quartz crystal, and T is the ambient temperature.

[0032] Optionally, the formula for calculating the phase difference is:

[0033]

[0034] In the formula, f os The frequency signal to be calibrated is f. os = f(T), k is the harmonic multiplier, m1 is the first divider multiplier, m2 is the second divider multiplier, f ref The standard frequency signal is t0, which is the initial phase time difference between the two input signals, and n is the number of measurement cycles.

[0035] Optionally, the formula for calculating the frequency signal to be calibrated is:

[0036]

[0037] Optionally, in the event of a power failure in the self-calibration device of the electricity meter clock, low-power compensation is performed based on the timekeeping signal and phase difference at the time of power failure, and the compensated timekeeping signal is output.

[0038] Therefore, this application provides a self-calibration device for an electricity meter clock. It compensates the frequency signal to be calibrated output by a common timekeeping crystal oscillator using a standard frequency signal output from a temperature-compensated crystal oscillator, thus outputting a timekeeping signal. This achieves a self-calibration method for the internal clock reference of the electricity meter, eliminating the need for external, remote, high-precision clock sources and saving system calibration workload.

[0039] The above and other objects, advantages and features of this application will become more apparent to those skilled in the art from the following detailed description of specific embodiments of this application in conjunction with the accompanying drawings. Attached Figure Description

[0040] The following sections will describe some specific embodiments of this application in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0041] Figure 1 This is a schematic diagram of the structure of the energy meter clock self-calibration device according to the first aspect of the embodiments of this application;

[0042] Figure 2 This is a schematic diagram illustrating the relationship between the frequency drift of a conventional time-keeping crystal oscillator and the ambient temperature, as described in the first aspect of the embodiments of this application.

[0043] Figure 3 This is a schematic diagram of the timed output adjusted by a temperature-compensated crystal oscillator at the power-on moment according to the first aspect of the embodiments of this application;

[0044] Figure 4 This is a schematic diagram of the process of using a common time-keeping crystal oscillator to process the time of power failure according to the first aspect of the embodiments of this application;

[0045] Figure 5 This is a schematic diagram of the timekeeping output process of the energy meter clock self-calibration device according to the first aspect of the embodiments of this application;

[0046] Figure 6 This is a schematic flowchart of the energy meter clock self-calibration method according to the second aspect of the embodiments of this application. Detailed Implementation

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other. This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] To enable those skilled in the art to better understand the present disclosure, the technical solutions of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present disclosure, and not all embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present disclosure.

[0049] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0050] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0051] Figure 1 This is a schematic diagram of the structure of the energy meter clock self-calibration device according to the first aspect of the embodiments of this application, with reference to... Figure 1 As shown, the self-calibration device for the electricity meter clock includes: a standard timekeeping crystal oscillator and a temperature-compensated crystal oscillator, wherein...

[0052] The standard frequency signal output by the temperature-compensated crystal oscillator is used to compensate the frequency signal to be calibrated output by the ordinary timekeeping crystal oscillator, and a timekeeping signal is output.

[0053] Optionally, the energy meter clock self-calibration device further includes: a first frequency divider, a frequency multiplier, a phase detector, a second frequency divider, a multiplier, a counter, and a phase-locked calculation module, wherein...

[0054] The temperature-compensated crystal oscillator outputs a standard frequency signal to the first frequency divider, and outputs a first frequency divided signal to the first input port of the phase detector according to the first frequency division factor.

[0055] A standard time-keeping crystal oscillator outputs the frequency signal to be calibrated to a frequency multiplier. Based on the multiplication factor, it outputs a multiplied signal to a second frequency divider. Based on the second division factor, the multiplied signal is divided, and the second divided signal is output to the second input port of the phase detector.

[0056] The phase detector performs phase detection on the first frequency division signal and the second frequency division signal, and outputs the phase difference signal between the first frequency division signal and the second frequency division signal;

[0057] The multiplier receives the phase difference signal and the standard frequency signal, multiplies them, and outputs the frequency pulse signal within the phase difference signal time period to the counter.

[0058] The counter counts the frequency pulse signal and inputs it into the phase-locked calculation module to obtain the phase difference corresponding to the phase difference signal;

[0059] The frequency multiplier is adjusted according to the phase difference until the phase difference between the first and second frequency division signals is equal to the initial phase difference. The frequency signal to be calibrated is then amplified and a timed signal is output based on the adjusted frequency multiplier.

[0060] Optionally, in the event of a power failure in the self-calibration device of the electricity meter clock, low-power compensation is performed based on the timekeeping signal and phase difference at the time of power failure, and the compensated timekeeping signal is output.

[0061] Specifically, refer to Figure 1 As shown, temperature-compensated crystal oscillators are generally high-frequency crystal oscillators (TCXO), while ordinary time-keeping crystal oscillators are low-frequency crystal oscillators. High-frequency crystal oscillators require frequency division and down-conversion to achieve phase-locked compensation with low-frequency crystal oscillators. Firstly, under normal power supply conditions, temperature-compensated crystal oscillators output a relatively standard frequency signal f. ref The first frequency divider receives the frequency signal f. ref The first frequency division factor is m1, making it become The first frequency division signal is input to the first input port 1 of the phase detector. The phase detector is used to compare the phase difference between two frequency signals, and can compare the rising edge phase time difference of the two input signals.

[0062] Subsequently, the ordinary time-keeping crystal oscillator outputs the frequency signal f to be calibrated. os The frequency multiplier, whose multiplication factor is controlled by the phase-locked loop (PLL) calculation module, is set to k. Therefore, the frequency signal output by the frequency multiplier here is kf. os By splitting the circuit, the frequency-doubled signal kf os The input is fed into the second frequency divider, with a division factor of m2, making it become... The second frequency division signal is input to the second input port 2 of the phase detector.

[0063] The phase detector performs phase detection on the first input port 1 and the second input port 2, and outputs the time phase difference signal t between the two signals. error It satisfies:

[0064]

[0065] Where t0 is the initial phase time difference between the two input signals, and n is the number of measurement cycles. error The signal is input to the multiplier and the temperature-compensated crystal oscillator, and the output is a relatively standard frequency signal f. ref Multiplying them together, we get t. error The frequency pulse signal within a time period. This signal is then counted by a counter and input to the phase calculation module to obtain t. error The value of k. By adjusting k, the following can be achieved:

[0066]

[0067] This achieves the calibration of ordinary time-keeping crystal oscillators and outputs standard time-keeping signals.

[0068] Furthermore, the frequency change of the ordinary time-keeping crystal oscillator (32.768 kHz) in this application due to changes in operating temperature can be approximated by a second-order equation:

[0069] f(T)=f0*[1-a*(T-T0) 2 ]

[0070] In the formula, f0 is the nominal frequency (32.768kHz), T0 is the standard temperature (25℃), a is the parabolic coefficient of the quartz crystal (typically 0.04 PPM / °C²), and T is the ambient temperature. The relationship between the frequency drift of a typical time-keeping crystal oscillator at 32.768kHz and the operating ambient temperature is as follows: Figure 2 As shown, the output frequency decreases as the temperature deviates from room temperature (25℃±3℃).

[0071] By f(T)=f0*[1-a*(T-T0)] 2 The formula shows that the current frequency f(T) is related to the temperature. Therefore, by reading the crystal oscillator's temperature T and the current frequency signal f to be calibrated, we can... os = f(T), from which f0 can be found. os The method for finding it is as follows:

[0072]

[0073] At 25℃, f0 is 32.768kHz. When the ordinary time-keeping crystal oscillator has not decayed, f0 = 32.768kHz according to the above calculation. When the RTC starts to decay, f0 < 32.768kHz according to the above calculation. As time goes by, f0 decays and gradually increases. When there is a power outage, f0 is still 32.768kHz, and f(T) = f0 * [1 - a * (T - T0)]. 2 If temperature compensation is applied, the clock will become increasingly off-target. Therefore, refer to... Figure 3 As shown, this scheme employs a timed output calibrated using a temperature-compensated crystal oscillator at power-on. (Reference) Figure 4 As shown, when the system loses power, considering the very low power consumption requirement of the energy meter, the power consumption of the temperature-compensated crystal oscillator cannot meet the requirement. Therefore, a low-frequency crystal oscillator of 32.768kHz is used for time processing. Considering the crystal oscillator attenuation problem, the last moment f0 is recorded and calculated after the power outage, and this value is used for low-power compensation after the power outage.

[0074] Therefore, refer to Figure 5 As shown, upon power-up, a high-precision clock output is provided. This high-precision clock corrects the low-frequency crystal oscillator of the RTC and records the attenuation of the low-frequency ordinary timekeeping crystal oscillator. Upon power-down, the latest attenuation value is used for effective compensation, achieving the goal of a high-precision clock. This method ensures that the energy meter maintains high-precision clock operation while considering power consumption, effectively solving the problem of inaccurate timekeeping due to crystal oscillator attenuation caused by long-term operation.

[0075] Power outages and fluctuations in power supply are common in power grids. During power outages, the internal clock reference of the electricity meter relies on a battery for power. However, the built-in battery of the electricity meter cannot support the long-term timekeeping of a high-performance crystal oscillator. Furthermore, traditional electricity meter clock circuits suffer from clock frequency drift and poor long-term stability, which can affect the accuracy of electricity metering during prolonged power outages. Our proposed method enables ordinary crystal oscillators to maintain timekeeping performance similar to that of temperature-compensated oscillators during long-term operation.

[0076] The internal clock reference of the electricity meter uses a self-calibration method, which does not rely on external, remote, high-precision clock sources for calibration, thus saving the system calibration workload.

[0077] also, Figure 6 This is a flowchart illustrating the self-calibration method for an electricity meter clock according to the second aspect of the embodiments of this application, with reference to... Figure 6 As shown, the self-calibration method 600 for the electricity meter clock includes:

[0078] Step 601: Output a standard frequency signal to the first frequency divider through a temperature-compensated crystal oscillator, and output a first frequency divided signal to the first input port of the phase detector according to the first frequency division factor;

[0079] Step 602: Output the frequency signal to be calibrated to the frequency multiplier through a normal time-keeping crystal oscillator, output the multiplied signal to the second frequency divider according to the multiplication factor, divide the multiplied signal according to the second division factor, and output the second divided signal to the second input port of the phase detector;

[0080] Step 603: Perform phase detection on the first frequency division signal and the second frequency division signal using a phase detector, and output the phase difference signal between the first frequency division signal and the second frequency division signal;

[0081] Step 604: Receive the phase difference signal and the standard frequency signal through a multiplier, multiply them, and output the frequency pulse signal within the phase difference signal time period to the counter;

[0082] Step 605: Count the frequency pulse signal using a counter and input it into the phase-locked calculation module to obtain the phase difference corresponding to the phase difference signal;

[0083] Step 606: Using the phase-locked calculation module, adjust the multiplication factor of the frequency multiplier according to the phase difference until the phase difference between the first and second frequency division signals is the initial phase difference. Amplify the frequency signal to be calibrated according to the adjusted multiplication factor as a timekeeping signal and output it.

[0084] Specifically, the technical solution and effects of the self-calibration method in the energy meter described in the second aspect of the embodiments of this application are all described in the first aspect of this application, and will not be repeated here.

[0085] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this disclosure. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0086] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0087] In the description of this disclosure, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this disclosure and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this disclosure; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0088] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A self-calibration device for an electricity meter clock, characterized in that, include: The system includes a standard time-keeping crystal oscillator, a temperature-compensated crystal oscillator, a first frequency divider, a frequency multiplier, a phase detector, a second frequency divider, a multiplier, a counter, and a phase-locked calculation module. The standard frequency signal output by the temperature-compensated crystal oscillator is used to compensate the frequency signal to be calibrated output by the ordinary time-keeping crystal oscillator, and a time-keeping signal is output. The temperature-compensated crystal oscillator outputs the standard frequency signal to the first frequency divider, and outputs the first frequency divided signal to the first input port of the phase detector according to the first frequency division factor. The ordinary time-keeping crystal oscillator outputs the frequency signal to be calibrated to the frequency multiplier, outputs a multiplied signal to the second frequency divider according to the multiplication factor, divides the multiplied signal according to the second division factor, and outputs the second divided signal to the second input port of the phase detector; The phase detector performs phase detection on the first frequency division signal and the second frequency division signal, and outputs the phase difference signal between the first frequency division signal and the second frequency division signal; The multiplier receives the phase difference signal and the standard frequency signal, multiplies them together, and outputs the frequency pulse signal within the time period of the phase difference signal to the counter. The counter counts the frequency pulse signal and inputs it into the phase-locked calculation module to obtain the phase difference corresponding to the phase difference signal; The phase-locked calculation module adjusts the multiplication factor of the frequency multiplier according to the phase difference until the phase difference between the first frequency division signal and the second frequency division signal is the initial phase difference. The frequency signal to be calibrated is amplified according to the adjusted multiplication factor and output as a timekeeping signal.

2. The self-calibration device for an electricity meter clock according to claim 1, characterized in that, The formula for the change of the frequency signal to be calibrated in the ordinary time-keeping crystal oscillator is: In the formula, f ( T () represents the frequency signal to be calibrated. f 0 represents the nominal frequency, i.e., timed output. T 0 is the standard temperature (25℃). a It is the parabolic coefficient of quartz crystal. T It refers to the ambient temperature.

3. The self-calibration device for an electricity meter clock according to claim 2, characterized in that, The formula for calculating the phase difference is: In the formula, The frequency signal to be calibrated, i.e. f ( T ), k It is a multiple of frequency. This is the first frequency division factor. This is the second frequency division factor. For standard frequency signals, It is the initial phase time difference between the two input signals. n This refers to the number of measurement cycles.

4. The self-calibration device for an electricity meter clock according to claim 3, characterized in that, The calculation formula for the frequency signal to be calibrated is: 。 5. The self-calibration device for an electricity meter clock according to claim 1, characterized in that, Also includes: The power-down compensation module is used to perform low-power compensation based on the timekeeping signal and the phase difference at the time of power failure when the energy meter clock self-calibration device loses power, and output the compensated timekeeping signal.

6. The method for self-calibrating the clock of an energy meter using the energy meter clock self-calibration device according to any one of claims 1-5, characterized in that, include: The standard frequency signal is output to the first frequency divider through a temperature-compensated crystal oscillator, and the first frequency divided signal is output to the first input port of the phase detector according to the first frequency division factor. The frequency signal to be calibrated is output through a regular time-keeping crystal oscillator to a frequency multiplier. The frequency multiplier signal is output to a second frequency divider according to the frequency multiplication factor. The frequency multiplier signal is divided according to the second frequency division factor, and the second frequency divided signal is output to the second input port of the phase detector. The phase detector performs phase detection on the first frequency division signal and the second frequency division signal, and outputs the phase difference signal between the first frequency division signal and the second frequency division signal; The multiplier receives the phase difference signal and the standard frequency signal, multiplies them together, and outputs the frequency pulse signal within the time period of the phase difference signal to the counter. The frequency pulse signal is counted by the counter and input to the phase-locked calculation module to obtain the phase difference corresponding to the phase difference signal; The phase-locked calculation module adjusts the multiplication factor of the frequency multiplier according to the phase difference until the phase difference between the first frequency division signal and the second frequency division signal is the initial phase difference. The frequency signal to be calibrated is amplified according to the adjusted multiplication factor and output as a timekeeping signal.

7. The method according to claim 6, characterized in that, Also includes: In the event of a power outage of the energy meter's clock self-calibration device, low-power compensation is performed based on the timekeeping signal at the time of power outage and the phase difference, and the compensated timekeeping signal is output.

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